This revision was automatically updated to reflect the committed changes.
Closed by commit rC321231: [ubsan] Diagnose noreturn functions which return
(authored by vedantk, committed by ).
Repository:
rC Clang
https://reviews.llvm.org/D40698
Files:
docs/UndefinedBehaviorSanitizer.rst
lib/CodeGen/CGBuiltin.cpp
lib/CodeGen/CGCall.cpp
lib/CodeGen/CGExpr.cpp
lib/CodeGen/CGExprCXX.cpp
lib/CodeGen/CodeGenFunction.h
test/CodeGen/ubsan-noreturn.c
test/CodeGenCXX/ubsan-unreachable.cpp
Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -1432,14 +1432,7 @@
case Builtin::BI__debugbreak:
return RValue::get(EmitTrapCall(Intrinsic::debugtrap));
case Builtin::BI__builtin_unreachable: {
- if (SanOpts.has(SanitizerKind::Unreachable)) {
- SanitizerScope SanScope(this);
- EmitCheck(std::make_pair(static_cast<llvm::Value *>(Builder.getFalse()),
- SanitizerKind::Unreachable),
- SanitizerHandler::BuiltinUnreachable,
- EmitCheckSourceLocation(E->getExprLoc()), None);
- } else
- Builder.CreateUnreachable();
+ EmitUnreachable(E->getExprLoc());
// We do need to preserve an insertion point.
EmitBlock(createBasicBlock("unreachable.cont"));
Index: lib/CodeGen/CodeGenFunction.h
===================================================================
--- lib/CodeGen/CodeGenFunction.h
+++ lib/CodeGen/CodeGenFunction.h
@@ -3288,11 +3288,15 @@
/// LLVM arguments and the types they were derived from.
RValue EmitCall(const CGFunctionInfo &CallInfo, const CGCallee &Callee,
ReturnValueSlot ReturnValue, const CallArgList &Args,
- llvm::Instruction **callOrInvoke = nullptr);
-
+ llvm::Instruction **callOrInvoke, SourceLocation Loc);
+ RValue EmitCall(const CGFunctionInfo &CallInfo, const CGCallee &Callee,
+ ReturnValueSlot ReturnValue, const CallArgList &Args,
+ llvm::Instruction **callOrInvoke = nullptr) {
+ return EmitCall(CallInfo, Callee, ReturnValue, Args, callOrInvoke,
+ SourceLocation());
+ }
RValue EmitCall(QualType FnType, const CGCallee &Callee, const CallExpr *E,
- ReturnValueSlot ReturnValue,
- llvm::Value *Chain = nullptr);
+ ReturnValueSlot ReturnValue, llvm::Value *Chain = nullptr);
RValue EmitCallExpr(const CallExpr *E,
ReturnValueSlot ReturnValue = ReturnValueSlot());
RValue EmitSimpleCallExpr(const CallExpr *E, ReturnValueSlot ReturnValue);
@@ -3747,6 +3751,10 @@
llvm::ConstantInt *TypeId, llvm::Value *Ptr,
ArrayRef<llvm::Constant *> StaticArgs);
+ /// Emit a reached-unreachable diagnostic if \p Loc is valid and runtime
+ /// checking is enabled. Otherwise, just emit an unreachable instruction.
+ void EmitUnreachable(SourceLocation Loc);
+
/// \brief Create a basic block that will call the trap intrinsic, and emit a
/// conditional branch to it, for the -ftrapv checks.
void EmitTrapCheck(llvm::Value *Checked);
Index: lib/CodeGen/CGExpr.cpp
===================================================================
--- lib/CodeGen/CGExpr.cpp
+++ lib/CodeGen/CGExpr.cpp
@@ -3076,6 +3076,17 @@
CGM.addUsedGlobal(F);
}
+void CodeGenFunction::EmitUnreachable(SourceLocation Loc) {
+ if (SanOpts.has(SanitizerKind::Unreachable)) {
+ SanitizerScope SanScope(this);
+ EmitCheck(std::make_pair(static_cast<llvm::Value *>(Builder.getFalse()),
+ SanitizerKind::Unreachable),
+ SanitizerHandler::BuiltinUnreachable,
+ EmitCheckSourceLocation(Loc), None);
+ }
+ Builder.CreateUnreachable();
+}
+
void CodeGenFunction::EmitTrapCheck(llvm::Value *Checked) {
llvm::BasicBlock *Cont = createBasicBlock("cont");
@@ -4616,7 +4627,7 @@
Callee.setFunctionPointer(CalleePtr);
}
- return EmitCall(FnInfo, Callee, ReturnValue, Args);
+ return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr, E->getExprLoc());
}
LValue CodeGenFunction::
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -2758,6 +2758,12 @@
void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI,
bool EmitRetDbgLoc,
SourceLocation EndLoc) {
+ if (FI.isNoReturn()) {
+ // Noreturn functions don't return.
+ EmitUnreachable(EndLoc);
+ return;
+ }
+
if (CurCodeDecl && CurCodeDecl->hasAttr<NakedAttr>()) {
// Naked functions don't have epilogues.
Builder.CreateUnreachable();
@@ -3718,7 +3724,8 @@
const CGCallee &Callee,
ReturnValueSlot ReturnValue,
const CallArgList &CallArgs,
- llvm::Instruction **callOrInvoke) {
+ llvm::Instruction **callOrInvoke,
+ SourceLocation Loc) {
// FIXME: We no longer need the types from CallArgs; lift up and simplify.
assert(Callee.isOrdinary());
@@ -4241,7 +4248,15 @@
EmitLifetimeEnd(llvm::ConstantInt::get(Int64Ty, UnusedReturnSize),
SRetPtr.getPointer());
- Builder.CreateUnreachable();
+ // Strip away the noreturn attribute to better diagnose unreachable UB.
+ if (SanOpts.has(SanitizerKind::Unreachable)) {
+ if (auto *F = CS.getCalledFunction())
+ F->removeFnAttr(llvm::Attribute::NoReturn);
+ CS.removeAttribute(llvm::AttributeList::FunctionIndex,
+ llvm::Attribute::NoReturn);
+ }
+
+ EmitUnreachable(Loc);
Builder.ClearInsertionPoint();
// FIXME: For now, emit a dummy basic block because expr emitters in
Index: lib/CodeGen/CGExprCXX.cpp
===================================================================
--- lib/CodeGen/CGExprCXX.cpp
+++ lib/CodeGen/CGExprCXX.cpp
@@ -89,7 +89,8 @@
*this, MD, This, ImplicitParam, ImplicitParamTy, CE, Args, RtlArgs);
auto &FnInfo = CGM.getTypes().arrangeCXXMethodCall(
Args, FPT, CallInfo.ReqArgs, CallInfo.PrefixSize);
- return EmitCall(FnInfo, Callee, ReturnValue, Args);
+ return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr,
+ CE ? CE->getExprLoc() : SourceLocation());
}
RValue CodeGenFunction::EmitCXXDestructorCall(
@@ -446,7 +447,7 @@
EmitCallArgs(Args, FPT, E->arguments());
return EmitCall(CGM.getTypes().arrangeCXXMethodCall(Args, FPT, required,
/*PrefixSize=*/0),
- Callee, ReturnValue, Args);
+ Callee, ReturnValue, Args, nullptr, E->getExprLoc());
}
RValue
Index: docs/UndefinedBehaviorSanitizer.rst
===================================================================
--- docs/UndefinedBehaviorSanitizer.rst
+++ docs/UndefinedBehaviorSanitizer.rst
@@ -124,8 +124,8 @@
- ``-fsanitize=signed-integer-overflow``: Signed integer overflow,
including all the checks added by ``-ftrapv``, and checking for
overflow in signed division (``INT_MIN / -1``).
- - ``-fsanitize=unreachable``: If control flow reaches
- ``__builtin_unreachable``.
+ - ``-fsanitize=unreachable``: If control flow reaches an unreachable
+ program point.
- ``-fsanitize=unsigned-integer-overflow``: Unsigned integer
overflows. Note that unlike signed integer overflow, unsigned integer
is not undefined behavior. However, while it has well-defined semantics,
Index: test/CodeGen/ubsan-noreturn.c
===================================================================
--- test/CodeGen/ubsan-noreturn.c
+++ test/CodeGen/ubsan-noreturn.c
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 %s -emit-llvm -fsanitize=unreachable -o - | FileCheck %s
+
+// CHECK-LABEL: @f(
+void __attribute__((noreturn)) f() {
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+}
Index: test/CodeGenCXX/ubsan-unreachable.cpp
===================================================================
--- test/CodeGenCXX/ubsan-unreachable.cpp
+++ test/CodeGenCXX/ubsan-unreachable.cpp
@@ -0,0 +1,81 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s -fsanitize=unreachable | FileCheck %s
+
+extern void __attribute__((noreturn)) abort();
+
+// CHECK-LABEL: define void @_Z14calls_noreturnv
+void calls_noreturn() {
+ abort();
+
+ // Check that there are no attributes on the call site.
+ // CHECK-NOT: call void @_Z5abortv{{.*}}#
+
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+}
+
+struct A {
+ // CHECK: declare void @_Z5abortv{{.*}} [[ABORT_ATTR:#[0-9]+]]
+
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A5call1Ev
+ void call1() {
+ // CHECK-NOT: call void @_ZN1A16does_not_return2Ev{{.*}}#
+ does_not_return2();
+
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+
+ // Test static members.
+ static void __attribute__((noreturn)) does_not_return1() {
+ // CHECK-NOT: call void @_Z5abortv{{.*}}#
+ abort();
+ }
+
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A5call2Ev
+ void call2() {
+ // CHECK-NOT: call void @_ZN1A16does_not_return1Ev{{.*}}#
+ does_not_return1();
+
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+
+ // Test calls through pointers to non-static member functions.
+ typedef void __attribute__((noreturn)) (A::*MemFn)();
+
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A5call3Ev
+ void call3() {
+ MemFn MF = &A::does_not_return2;
+ (this->*MF)();
+
+ // CHECK-NOT: call void %{{.*}}#
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+
+ // Test regular members.
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A16does_not_return2Ev({{.*}})
+ // CHECK-SAME: [[DOES_NOT_RETURN_ATTR:#[0-9]+]]
+ void __attribute__((noreturn)) does_not_return2() {
+ // CHECK-NOT: call void @_Z5abortv(){{.*}}#
+ abort();
+
+ // CHECK: call void @__ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+
+ // CHECK: call void @__ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+};
+
+// CHECK: define linkonce_odr void @_ZN1A16does_not_return1Ev() [[DOES_NOT_RETURN_ATTR]]
+
+void force_irgen() {
+ A a;
+ a.call1();
+ a.call2();
+ a.call3();
+}
+
+// CHECK-NOT: [[ABORT_ATTR]] = {{[^}]+}}noreturn
+// CHECK-NOT: [[DOES_NOT_RETURN_ATTR]] = {{[^}]+}}noreturn
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